Biomaterial Database

Effect of low root temperature on hydraulic conductivity of rice plants and the possible role of aquaporins. 2008

Mari Murai-Hatano, and Tsuneo Kuwagata, and Junko Sakurai, and Hiroshi Nonami, and Arifa Ahamed, and Kiyoshi Nagasuga, and Toshinori Matsunami, and Keiko Fukushi, and Masayoshi Maeshima, and Masumi Okada

National Agricultural Research Center for Tohoku Region, Climate Change Research Team, Morioka, 020-0198 Japan. murai@affrc.go.jp

The role of root temperature T(R) in regulating the water-uptake capability of rice roots and the possible relationship with aquaporins were investigated. The root hydraulic conductivity Lp(r) decreased with decreasing T(R) in a measured temperature range between 10 degrees C and 35 degrees C. A single break point (T(RC) = 15 degrees C) was detected in the Arrhenius plot for steady-state Lp(r). The temperature dependency of Lp(r) represented by activation energy was low (28 kJ mol(-1)) above T(RC), but the value is slightly higher than that for the water viscosity. Addition of an aquaporin inhibitor, HgCl(2), into root medium reduced osmotic exudation by 97% at 25 degrees C, signifying that aquaporins play a major role in regulating water uptake. Below T(RC), Lp(r) declined precipitously with decreasing T(R) (E(a) = 204 kJ mol(-1)). When T(R) is higher than T(RC), the transient time for reaching the steady-state of Lp(r) after the immediate change in T(R) (from 25 degrees C) was estimated as 10 min, while it was prolonged up to 2-3 h when T(R) < T(RC). The Lp(r) was completely recovered to the initial levels when T(R) was returned back to 25 degrees C. Immunoblot analysis using specific antibodies for the major aquaporin members of PIPs and TIPs in rice roots revealed that there were no significant changes in the abundance of aquaporins during 5 h of low temperature treatment. Considering this result and the significant inhibition of water-uptake by the aquaporin inhibitor, we hypothesize that the decrease in Lp(r) when T(R) < T(RC) was regulated by the activity of aquaporins rather than their abundance.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009997	Osmotic Pressure	The pressure required to prevent the passage of solvent through a semipermeable membrane that separates a pure solvent from a solution of the solvent and solute or that separates different concentrations of a solution. It is proportional to the osmolality of the solution.	Osmotic Shock,Hypertonic Shock,Hypertonic Stress,Hypotonic Shock,Hypotonic Stress,Osmotic Stress,Hypertonic Shocks,Hypertonic Stresses,Hypotonic Shocks,Hypotonic Stresses,Osmotic Pressures,Osmotic Shocks,Osmotic Stresses,Pressure, Osmotic,Pressures, Osmotic,Shock, Hypertonic,Shock, Hypotonic,Shock, Osmotic,Shocks, Hypertonic,Shocks, Hypotonic,Shocks, Osmotic,Stress, Hypertonic,Stress, Hypotonic,Stress, Osmotic,Stresses, Hypertonic,Stresses, Hypotonic,Stresses, Osmotic
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D012275	Oryza	A genus of grass family (Poaceae) that include several rice species.	Oryza sativa,Rice,Rices
D014867	Water	A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Hydrogen Oxide
D052584	Xylem	Plant tissue that carries water up the root and stem. Xylem cell walls derive most of their strength from LIGNIN. The vessels are similar to PHLOEM sieve tubes but lack companion cells and do not have perforated sides and pores.	Xylems
D018517	Plant Roots	The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)	Plant Bulbs,Plant Root,Bulb, Plant,Bulbs, Plant,Plant Bulb,Root, Plant,Roots, Plant
D020346	Aquaporins	A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.	Aquaporin,Water Channel,Water Channel Protein,Water Channel Proteins,Water Channels,Channel Protein, Water,Channel Proteins, Water,Channel, Water,Channels, Water,Protein, Water Channel,Proteins, Water Channel